JPH08214395A - Repulsive magnetic circuit of speaker - Google Patents

Abstract

PURPOSE: To provide the repulsive magnetic circuit of a speaker capable of increasing valid magnetic fluxes related to the driving energy of a voice coil without increasing the volume of a magnet. CONSTITUTION: The two magnets M1 and M2 are arranged holding a center plate P composed of a ferromagnetic body there between so as to let the same pole face each other, the voice coil is arranged at the outer periphery of the center plate P so as to be positioned within a repulsive magnetic field by both magnets M1 and M2 and a diaphragm is driven by the voice coil. Then, the magnets M1 and M2 are turned to a shape by which a surface 11 on the opposite side of the surface 12 to be in contact with the center plate P is not parallel to the contact surface 12 of the center plate P and the magnets.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repulsive magnetic circuit in a repulsive magnetic circuit type speaker, and more particularly to a repulsive magnetic circuit in which the shape and size ratio of its magnet and center plate are optimally set.

[0002]

2. Description of the Related Art Conventionally, a center plate made of a magnetic material is sandwiched between two magnets so that the same poles face each other, and a voice is placed on the outer periphery of the center plate so as to be positioned within the repulsive magnetic field of both magnets. There is a repulsive magnetic circuit type speaker in which a coil is arranged and a diaphragm is driven by the voice coil. We have also improved this type of speaker and have made various proposals previously.

One example is shown in FIG. 5, in which two magnets M1 and M2 are arranged with a center plate P made of a ferromagnetic material sandwiched therebetween so that the same poles face each other. The voice coil 1 is arranged on the outer circumference of the center plate P so as to be located at the position, and the diaphragm 2 is driven by the voice coil 1. In the figure, 3 is a damper, 4 is a holder, 5 is a frame, 6 is a coil bobbin, 7 is a coil portion, and 8 is a dust cap.

Generally, a conventional repulsive magnetic circuit is constructed as shown in FIG. 3, and the dimensional ratio of the magnets M1, M2 and the center plate P is 10 on the outer circumference of the center plate P.
When set to 0, the outer diameters of the magnets M1 and M2 are 96, the inner diameter is 34, the thickness is 26, and the inner diameter of the center plate P is 3
4, the thickness is 23. Therefore, both magnets M1, M
In No. 2, the surface in contact with the center plate P and the surface on the opposite side are parallel to each other.

[0005]

The conventional center plate P has an outer circumference of φ35 mm, an effective magnetic flux area related to the voice coil of φ36 mm and a length of 8 mm. A magnet having an energy of 32 mega gauss Oersted and a center plate are equivalent to S40C. When a ferromagnetic material having the magnetic properties of 1 is used and the energy amount is calculated by integrating in the effective magnetic flux region, it is about 2400 gauss cm.

The efficiency of a speaker having a repulsive magnetic circuit increases as the amount of energy increases. To increase this amount of energy, the volume of the magnet should be increased to increase the amount of energy that the magnet has, but the method of increasing the volume of the magnet increases the cost by the increase of the volume of the magnet, The mass of the whole circuit increases.

Therefore, an object of the present invention is to provide a repulsive magnetic circuit of a speaker which can increase the effective magnetic flux related to the driving energy of the voice coil without increasing the volume of the magnet.

[0008]

In the repulsive magnetic circuit of the speaker of the present invention, two magnets are arranged so as to face each other with the same pole sandwiching a center plate made of a ferromagnetic material. In the repulsive magnetic circuit type speaker, in which a voice coil is arranged on the outer periphery of the center plate so as to be located at, and the diaphragm is driven by the voice coil, at least one magnet,
Preferably, both magnets are configured such that the surface on the side opposite to the surface in contact with the center plate is not parallel to the contact surface between the center plate and the magnet, and the magnet has a lower outer peripheral side.

At this time, when the outer diameter of the center plate determined by the set position of the voice coil is 100, the outer diameter of the magnet is 96 to 100 and the inner diameter is 17 to.
23, the thickness of the outer peripheral portion is set to 14 to 20, the thickness of the inner peripheral portion is set to 31 to 37, the inner diameter of the center plate is set to 10 to 17, and the thickness is set to 13 to 19.

[0010]

[Function] The magnet is an Nd.Fe.B anisotropic sintered magnet having a residual magnetic flux density of 1.16T and a relative permeability of 1.05, and the ferromagnetic center plate has magnetic characteristics equivalent to S40C. When the non-linear magnetic field analysis in which the variables are controlled by the optimization program is performed using the material having the above, and the outer diameter of the center plate determined by the set position of the voice coil is 100, the outer diameter of the magnet is 96 to 100, inner diameter 17-23, outer peripheral thickness 14-20, inner peripheral thickness 31-37, center plate inner diameter 10-17, thickness 13-19
It has been found that the energy amount increases without increasing the mass of the magnet by setting the dimensional ratio of.

Further, since the height of the outer circumference of the magnet is low, which corresponds to the shape of the dust cap, when the same dust cap is attached to the diaphragm, the amplitude of the diaphragm can be set to a large value, which is larger than the conventional one. Can be used for large input specifications. Moreover, when the dust cap having the same curvature is used, the diameter of the dust cap can be made smaller than that of the conventional one, so that the effective area of the diaphragm is increased and the efficiency is increased.

[0012]

1 and 2 are sectional views showing an embodiment of a repulsive magnetic circuit of a speaker according to the present invention, in which a magnet and a center plate are set to most preferable dimensions.
In the figure, P is a center plate made of a ferromagnetic material,
M1 and M2 are two magnets arranged so that the same poles face each other across the center plate P. As in the conventional case, the center plate P is positioned so as to be positioned within the repulsive magnetic field of both magnets M1 and M2. A voice coil is arranged on the outer periphery of the diaphragm and the diaphragm is driven by the voice coil.

In the present invention, the magnets M1 and M2
Has a shape in which the surface 11 opposite to the surface 12 that contacts the center plate P is not parallel to the contact surface 12 of the center plate and the magnet. Therefore, the outer surface of the surface 11 opposite to the surface 12 that contacts the center plate P is low.

In the embodiment of FIGS. 1 and 2, the magnets M1 and M2 are Nd.Fe.B anisotropic sintered magnets having residual magnetic flux density of 1.16T and relative permeability of 1.05. A material having magnetic characteristics equivalent to S40C is used for the ferromagnetic center plate, and when the outer circumference of the center plate is φ35 mm and the effective magnetic flux area ME is 8 mm, the outer diameter of the magnet is φ34.9 and the inner diameter is φ7. 0,
The outer peripheral thickness is 5.9 mm, the inner peripheral thickness is 11.9 mm,
The center plate has an inner diameter of φ4.9 mm and a thickness of 5.6.
mm.

The values of the embodiments shown in FIGS. 1 and 2 are obtained by calculation by performing nonlinear magnetic field analysis with variable control by an optimization program. As a result, FIG. 1 and FIG.
It was found that the amount of energy becomes the largest when the magnet shape as shown in is used. The amount of energy at this time is 2570 gauss cm, and the energy efficiency is about 7 compared with the conventional one having the magnet of the same volume.
% Up.

Although the rate of increase in energy efficiency is somewhat lowered, the outer diameter of the center plate determined by the set position of the voice coil is 100, which is not limited to the range of the values in the above embodiment, and the magnet's Outer diameter is 96 ~
100, inner diameter 17-23, outer peripheral thickness 14-2
0, the inner peripheral part has a thickness of 31 to 37, the center plate has an inner diameter of 10 to 17, and the thickness is within the range of 13 to 19, the energy efficiency can be improved.
It has been found that the effect is reduced when it is out of the above range.

Further, as shown in FIG. 2, the magnet M1
Since the height on the outer peripheral side is low and corresponds to the shape of the dust cap 8, when the same dust cap 8 is attached to the diaphragm, the amplitude can be increased to the position indicated by the virtual line 8a. Therefore, the amplitude of the diaphragm can be set large, and the input specifications can be made larger than those of the conventional one shown in FIG. Moreover, when the dust cap 8 having the same curvature is used, the diameter of the dust cap 8 can be made smaller than that of the conventional one shown in FIG. 4, so that the effective area of the diaphragm is increased and the efficiency can be improved.

[0018]

The speaker repulsion magnetic circuit of the present invention has the following effects. (1) The amount of energy applied to the voice coil can be increased without increasing the mass of the magnet, and the efficiency of the speaker can be increased. (2) Since the mass of the magnet does not change, the performance called efficiency can be improved without increasing the cost of the raw material cost of the speaker. (3) If the same efficiency as that of the conventional one is secured, the amount of magnets can be small, so that the weight can be reduced and the cost can be reduced. (4) The height of the outer circumference of the magnet is low,
Since it corresponds to the shape of the dust cap, when the same dust cap is attached to the diaphragm, the amplitude of the diaphragm can be set to a large value, and the input specifications can be made larger than before. Moreover, when the dust cap having the same curvature is used, the diameter of the dust cap can be made smaller than that of the conventional one, so that the effective area of the diaphragm is increased and the efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a repulsive magnetic circuit of a speaker according to the present invention.

FIG. 2 is a cross-sectional view of a main part showing a relationship with a dust cap attached to the diaphragm.

FIG. 3 is a cross-sectional view of a conventional repulsive magnetic circuit.

FIG. 4 is a sectional view of a main part showing a relationship with a dust cap in a conventional repulsive magnetic circuit.

FIG. 5 is a cross-sectional view of the repulsive magnetic circuit type speaker that we previously proposed.

[Explanation of symbols]

P Center plate M1, M2 Magnet 11 Surface opposite to the surface of the magnet that contacts the center plate. 12 Contact surface with the center plate of the magnet.

Claims (4)

[Claims] 1. A voice coil is arranged on the outer circumference of a center plate so that two magnets are arranged so as to face each other across a center plate made of a ferromagnetic material and the magnets are located in a repulsive magnetic field. In the repulsive magnetic circuit type speaker configured to drive the diaphragm with the voice coil, at least one of the magnets has a surface opposite to the surface contacting the center plate with respect to the contact surface between the center plate and the magnet. A repulsive magnetic circuit for a speaker, which has a non-parallel shape. 2. The repulsive magnetic circuit for a speaker according to claim 1, wherein both the upper surface of the upper magnet and the lower surface of the lower magnet are not parallel to the contact surface with the center plate. 3. The repulsive magnetic circuit for a speaker according to claim 1 or 2, wherein a surface opposite to a surface contacting the center plate has a lower outer peripheral side. 4. The repulsive magnetic circuit for a speaker according to claim 1, wherein the outer diameter of the magnet is 96 to 100, when the outer diameter of the center plate determined by the set position of the voice coil is 100. Inner diameter is 17 ~
23, the thickness of the outer peripheral portion is 14 to 20, the thickness of the inner peripheral portion is 31 to 37, the inner diameter of the center plate is 10 to 17, and the thickness is 13 to 19. Repulsive magnetic circuit of the speaker.